1) You can search the Timeline panel for 'PSD' or 'AI'. Use the hourglass icon on the top of the panel, or press Ctrl+F (Windows) or Cmd+F (macOS).

2) Use label colors to simplify selections. You can click the little color swatch on a layer in the timeline panel to set its label color. You could manually set different label colors for your PSD and AI layers. With that done, you can click the label color of one of the items you wish to select and choose 'Select Label Group' to select all layers in the comp with that label color.